Heat Transfer and Pressure Drop Performance of Finned Tube Bundles

1985 ◽  
Vol 107 (1) ◽  
pp. 205-213 ◽  
Author(s):  
P. W. Eckels ◽  
T. J. Rabas
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Air Conditioning ◽  
High Heat ◽  
Finned Tube ◽  
Tip Clearance ◽  
Finned Tubes ◽  
Pin Fin ◽  
High Heat Transfer ◽  
Air Cooled Heat Exchanger

The heat transfer and pressure drop performance of two types of finned tubes used in the air-conditioning industry are reported for 14 different bundle configurations. Twelve of these configurations contained a new type of finned tube called K-Y and two contained a more conventional pin fin. A unique characteristic of all these configurations is zero or negative fin-tip clearances. A comparison of the performance of these air-conditioning type finned tubes with negative fin-tip clearance is then made with the performance of typical air-cooled heat exchanger tubes used in the process and power industries. Both the heat transferred and the pressure drop are substantially higher with the air-conditioning configurations; the heat transfer coefficient is superior even to plain tubes. The very high heat transfer performance is more the result of the negative fin-tip clearance than the fin shape or type.

Heat Transfer and Pressure Drop of Typical Air Cooler Finned Tubes

1985 ◽  
Vol 107 (1) ◽  
pp. 198-204 ◽  
Author(s):  
P. W. Eckels ◽  
T. J. Rabas
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Finned Tube ◽  
Tip Clearance ◽  
Published Data ◽  
Air Cooling ◽  
Base Thickness ◽  
Finned Tubes ◽  
Air Cooler ◽  
The Heat Transfer Coefficient

The heat transfer and pressure drop performance of heat exchangers fabricated from helically wrapped finned tubes with an equilateral triangular pitch arrangement are reported for one through five rows. Two finned tube types were tested, one with a “T” foot and the other with an overlapped “L” foot. The dimensions of both finned tubes were similar and were typical of those used in air-cooling applications. The tube diameter was 25.4 mm; the fin height was 15.87 mm; the fin number was 0.41/mm; and the fin-tip clearance was 6.35 mm. The fin base thickness was 0.38 mm and was tapered to half the base thickness at the fin outside diameter. No difference in the thermal performance of the two finned tube types could be detected. Both the heat transfer coefficient and pressure drop were found to increase with the number of tube rows. These results were then compared to other published data.

Effect of Corrugated Orifice and Pin-Fin on Multiple Array Impingement Cooling With Low Nozzle to Target Distance

2014 ◽  
Author(s):  
Li Yang ◽  
Weihong Li ◽  
Zhongran Chi ◽  
Jing Ren ◽  
Hongde Jiang
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Conjugate Heat Transfer ◽  
High Heat ◽  
Inlet Temperature ◽  
Impingement Cooling ◽  
Pin Fin ◽  
High Heat Transfer ◽  
Pin Fins ◽  
Heat Transfer Simulation

Impingement cooling is widely used in turbine vanes and combustors. With the increase of turbine inlet temperature, high heat transfer coefficient and low pressure drop are required for cooling structures. A series of new impingement configurations combined with corrugated orifice and pin-fins were developed in the present work. Both transient liquid crystal (TLC) and pressure measurement were applied on the impingement cooling structures. A 3D numerical method was also used for conjugate heat transfer simulation. Corrugated orifice helps decrease the pressure drop by decreasing the speed of cross flow. Experimental data show that, corrugated orifice is helpful in reducing pin-fin induced pressure drop but contributes little to heat transfer. Pin-fins increases both the heat transfer and pressure drop lightly. Conjugate heat transfer simulation shows that pin-fins significantly reduce the metal temperature by conduction. Structures with pin-fins can make a good use of the large surface area of corrugated orifices.

Influence of tip clearance and cavity depth on heat transfer in a cutback squealer tip

2020 ◽  
pp. 095441002096469
Author(s):  
Weijie Wang ◽  
Shaopeng Lu ◽  
Hongmei Jiang ◽  
Qiusheng Deng ◽  
Jinfang Teng ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Suction Side ◽  
High Heat ◽  
Tip Clearance ◽  
Tip Leakage Flow ◽  
Trailing Edge ◽  
Cavity Depth ◽  
High Heat Transfer ◽  
Blade Tip ◽  
High Heat Transfer Coefficient

Numerical simulations are conducted to present the aerothermal performance of a turbine blade tip with cutback squealer rim. Two different tip clearance heights (0.5%, 1.0% of the blade span) and three different cavity depths (2.0%, 3.0%, and 6.0% of the blade span) are investigated. The results show that a high heat transfer coefficient (HTC) strip on the cavity floor appears near the suction side. It extends with the increase of tip clearance height and moves towards the suction side with the increase of cavity depth. The cutback region near the trailing edge has a high HTC value due to the flush of over-tip leakage flow. High HTC region shrinks to the trailing edge with the increase of cavity depth since there is more accumulated flow in the cavity for larger cavity depth. For small tip clearance cases, high HTC distribution appears on the pressure side rim. However, high HTC distribution is observed on suction side rim for large tip clearance height. This is mainly caused by the flow separation and reattachment on the squealer rims.

Tube Banks Heat Transfer Enhancement Using Conical Fins

2010 ◽  
Author(s):  
Ignacio Carvajal-Mariscal ◽  
Florencio Sanchez-Silva ◽  
Georgiy Polupan
Keyword(s):  
Heat Transfer ◽  
Heat Exchange ◽  
Pressure Drop ◽  
Finned Tube ◽  
Hot Water ◽  
Experimental Results ◽  
Tube Bank ◽  
Finned Tubes ◽  
Tube Banks ◽  
Annular Fins

In this work the heat transfer and pressure drop experimental results obtained in a two step finned tube bank with conical fins are presented. The tube bank had an equilateral triangle array composed of nine finned tubes with conical fins inclined 45 degrees in respect with the tube axis. The heat exchange external area of a single tube is approximately 0.07 m2. All necessary thermal parameters, inlet/outlet temperatures, mass flows, for the heat balance in the tube bank were determined for different air velocities, Re = 3400–18400, and one constant thermal charge provided by a hot water flow with a temperature of 80 °C. As a result, the correlations for the heat transfer and pressure drop calculation were obtained. The experimental results were compared against the analytical results for a tube bank with annular fins with the same heat exchange area. It was found that the proposed tube bank using finned tubes with conical fins shows an increment of heat transfer up to 58%.

Heat Transfer Characteristics of a Flow Passage With Long Pin Fins and Improving Heat Transfer Coefficient by Adding Turbulence Promoters on a Endwall

2001 ◽  
Author(s):  
K. Takeishi ◽  
T. Nakae ◽  
K. Watanabe ◽  
M. Hirayama
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Aspect Ratio ◽  
Transfer Coefficient ◽  
High Heat ◽  
Atmospheric Conditions ◽  
Pin Fin ◽  
High Heat Transfer ◽  
Turbine Vanes ◽  
Pin Fins

Pin fins are normally used for cooling the trailing edge region of a turbine, where their aspect ratio (height H/diameter D) is characteristically low. In small turbine vanes and blades, however, pin fins may also be located in the middle region of the airfoil. In this case, the aspect ratio can be quite large, usually obtaining values greater than 4. Heat transfer tests, which are conducted under atmospheric conditions for the cooling design of turbine vanes and blades, may overestimate the heat transfer coefficient of the pin-finned flow channel for such long pin fins. The fin efficiency of a long pin fin is almost unity in a low heat transfer situation as it would be encountered under atmospheric conditions, but can be considerably lower under high heat transfer conditions and for pin fins made of low thermal conductivity material. A series of tests with corresponding heat transfer models has been conducted in order to clarify the heat transfer characteristics of the long pin-finned flow channel. It is assumed that heat transfer coefficients can be predicted by the linear combination of two heat transfer equations, which were separately developed for the pin fin surface and for tubes in crossflow. To confirm the suggested combined equations, experiments have been carried out, in which the aspect ratio and the thermal conductivity of the pin were the test parameters. To maintain a high heat transfer coefficient for a long pin fin under high-pressure conditions, the heat transfer was augmented by adding a turbulence promoter on the pin-finned endwall surface. A corresponding equation that describes this situation has been developed. The predicted and measured values showed good agreement. In this paper, a comprehensive study on the heat transfer of a long pin-fin array will be presented.

scholarly journals Design Evaluation for a Finned-Tube CO2 Gas Cooler in Residential Applications

Energies ◽  
2020 ◽  
Vol 13 (10) ◽  
pp. 2428 ◽  
Author(s):  
Charalampos Alexopoulos ◽  
Osama Aljolani ◽  
Florian Heberle ◽  
Tryfon C. Roumpedakis ◽  
Dieter Brüggemann ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Pressure Drop ◽  
Transfer Coefficient ◽  
Air Conditioning ◽  
Design Procedure ◽  
Finned Tube ◽  
Co2 Gas ◽  
Ambient Temperatures ◽  
Overall Heat Transfer Coefficient

Towards the introduction of environmentally friendlier refrigerants, CO2 cycles have gained significant attention in cooling and air conditioning systems in recent years. In this context, a design procedure for an air finned-tube CO2 gas cooler is developed. The analysis aims to evaluate the gas cooler design incorporated into a CO2 air conditioning system for residential applications. Therefore, a simulation model of the gas cooler is developed and validated experimentally by comparing its overall heat transfer coefficient. Based on the model, the evaluation of different numbers of rows, lengths, and diameters of tubes, as well as different ambient temperatures, are conducted, identifying the most suitable design in terms of pressure losses and required heat exchange area for selected operational conditions. The comparison between the model and the experimental results showed a satisfactory convergence for fan frequencies from 50 to 80 Hz. The absolute average deviations of the overall heat transfer coefficient for fan frequencies from 60 to 80 Hz were approximately 10%. With respect to the gas cooler design, a compromise between the bundle area and the refrigerant pressure drop was necessary, resulting in a 2.11 m2 bundle area and 0.23 bar refrigerant pressure drop. In addition, the analysis of the gas cooler’s performance in different ambient temperatures showed that the defined heat exchanger operates properly, compared to other potential gas cooler designs.

An Analytical Study of the Optimized Performance of an Impingement Heat Sink

2004 ◽  
Vol 126 (4) ◽  
pp. 528-534 ◽  
Author(s):  
S. B. Sathe ◽  
B. G. Sammakia
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Heat Sink ◽  
High Performance ◽  
Cross Flow ◽  
High Heat ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
High Heat Transfer ◽  
Flow Through

The results of a study of a new and unique high-performance air-cooled impingement heat sink are presented. An extensive numerical investigation of the heat sink performance is conducted and is verified by experimental data. The study is relevant to cooling of high-power chips and modules in air-cooled environments and applies to workstations or mainframes. In the study, a rectangular jet impinges on a set of parallel fins and then turns into cross flow. The effects of the fin thickness, gap nozzle width and fin shape on the heat transfer and pressure drop are investigated. It is found that pressure drop is reduced by cutting the fins in the central impingement zone without sacrificing the heat transfer due to a reduction in the extent of the stagnant zone. A combination of fin thicknesses of the order of 0.5 mm and channel gaps of 0.8 mm with appropriate central cutout yielded heat transfer coefficients over 1500 W/m2 K at a pressure drop of less than 100 N/m2, as is typically available in high-end workstations. A detailed study of flow-through heat sinks subject to the same constraints as the impingement heat sink showed that the flow-through heat sink could not achieve the high heat transfer coefficients at a low pressure drop.

Study on Free Convection Heat Transfer in a Finned Tube Array

2015 ◽  
Vol 23 (01) ◽  
pp. 1550007 ◽  
Author(s):  
Ryoji Katsuki ◽  
Tsutomu Shioyama ◽  
Chikako Iwaki ◽  
Tadamichi Yanazawa
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Heat Exchanger ◽  
Transfer Coefficient ◽  
Finned Tube ◽  
Average Heat Transfer Coefficient ◽  
Average Heat ◽  
Finned Tubes ◽  
Air Cooled Heat Exchanger ◽  
The Heat Transfer Coefficient

We have been developing a free convection air cooled heat exchanger without power supply to improve economic efficiency and mechanical reliability. However, this heat exchanger requires a larger installation area than the forced draft type air cooled heat exchanger since a large heating surface is needed to compensate for the small heat transfer by natural convection. Therefore, we have been investigating a heat exchanger consisting of an array of finned tubes and chimney to increase the heat transfer coefficient. Since the heat transfer characteristics of finned tube arrays have not been clarified, we conducted experiments with a finned tube array to determine the relation between the configuration of finned tubes and the heat transfer coefficient of a tube array. The results showed that the average heat transfer coefficient increased with pitch in the vertical direction, and became constant when the pitch was over five times the fin diameter. The average heat transfer coefficient was about 1.4 times higher than that of a single finned tube in free space. The ratio of the average heat transfer coefficient of the finned tube array with chimney to that of a single finned tube was found to be independent of the difference in temperature between the tube surface and air.

An Investigation of Heat Transfer and Pressure Drop Enhancement of Various Perforated Circular Finned Tubes at Different Tube Tilt Angles

2021 ◽  
pp. 10295-10338
Author(s):  
Yahya Yaser Shanyour AL-Salman, Ali Sabri Abbas
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Heat Transfer Rate ◽  
Tilt Angle ◽  
Transfer Rate ◽  
Performance Criterion ◽  
Finned Tube ◽  
Finned Tubes ◽  
Global Performance

The thermal and flow performance of the circular annular finned tube heat exchanger with perforated fins were investigated numerically using ANSYS Fluent 2020 software, RNG k-e model with enhanced wall treatment, global performance criterion was introduced as evaluation factor of the heat exchanger performance, the parameters to be investigated were the number of holes, size of hole, tilt angle of the finned tube, fin height and spacing between fins. Agreement was found with literature that the tilt angle causes increase in heat transfer rate and increase in the pressure drop as well, but the change the global performance criterion as function to tilt angle depends on the fin heights, for higher fin heights the effective change of the pressure drop become greater than the increase in the heat transfer rate and the contrast occur in the cases of smaller fin heights, we have found that the perforation in tilted annular circular finned tubes causes an increase in the heat transfer rate and an enhancement in the total heat exchanger performance, increasing the number of holes will enhance the performance of the heat exchanger and the spacing increase reduces the heat exchanger performance.

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